Claudia Boyle and Robin Adams in The Last Hotel. Photograph: Murdo Macleod

A gas cylinder, a tube, a plastic bag and a few coloured balloons to cheer the final journey: even diehard optimists would find the fixtures and fittings in this desolate hotel room enough to bring on the blues. Yet the world premiere of The Last Hotel, a collaboration between the composer Donnacha Dennehy and playwright Enda Walsh (whose Ballyturk ran at the National Theatre last year), struck a bracing and eclectically noisy blow as the first operatic offering of Edinburgh international festival 2015.

In his inaugural season as EIF director, Fergus Linehan has gone back to his Dublin roots (he directed a play by Walsh more than a decade ago) and made the Edinburgh air crackle with cryptic Irish energy and boggy gloom. “I know what the audience wants and I can’t give it to them,” Linehan said in an interview with the Guardian on his appointment, acknowledging the prohibitively expensive desire for star names and lavish productions. An opera about euthanasia with a karaoke scene was probably not high on anyone’s list of “must haves”.

An opera about euthanasia with a karaoke scene was probably not high on anyone’s list of “must haves”

Co-commissioned by Landmark Productions and Wide Open Opera, The Last Hotel starts with a caretaker (actor Mikel Murfi) sweeping the floor on an empty stage. Two sopranos and a baritone, plus Dennehy’s 12-strong Crash Ensemble, which includes piano, accordion and electric guitar, combine explosively for some 90 minutes (10 minutes too long) without an interval, expertly conducted by André de Ridder. A generic, suburban Husband and Wife – he a gas fitter, she a creature crushed by life and longing for love – travel to the hotel of the title to help a glamorous Irishwoman (Claudia Boyle), apparently once the husband’s lover, to kill herself. Events turn out madly, sometimes hilariously, occasionally tediously, and not quite as anyone expected. Robin Adams and Katherine Manley, equally versatile and well matched, excel as the married couple. Boyle – the best ingredient, as Mabel, in ENO’s recent Pirates of Penzance – plays the Woman, at once brazen and fragile. “The kids said I would die fat,” she intones, in one of many memorable one-liners.

Musically intoxicating, a riot of postminimalism and hooley, Denny’s score favours high vocal lines which rise at the end of phrases (John Adams uses a similar technique). Prolonged fortissimos bubble up urgently. A drum thuds loud enough to deafen the dead. The influences of Bang on a Can and Louis Andriessen are discernible but the style is very much Dennehy’s. Near the end, the two women – now almost indistinguishable – sing together, voices intertwining in remote, almost glassy lament. Walsh’s terse libretto is audible most of the time, this witty, quirky skeleton given flesh by the music, and by a clear staging by the writer himself, designed by Jamie Vartan with lighting by Adam Silverman. The Last Hotel neither champions nor condemns euthanasia. It invites you to think with head and heart. Catch it in London (ROH Linbury Studio, 9-17 October) or, why not, New York (St Anne’s Warehouse, 8-17 January).

Earlier the same day, Rudolf Buchbinder played Beethoven’s epic Hammerklavier Op 106 in the creamy, columned splendour of Playfair Library, part of the Austrian pianist’s complete Beethoven sonata series. This is Buchbinder’s 49th account of the 32-work cycle – he began in the 1970s – so he knows the notes and rather more. Meticulous and carefree, he makes the music his own while always serving the composer. Tempi were brisk, sometimes too fast for comfort but certainly spirited, with dramatic pauses before galloping off once more.

In this heavily carpeted, long, narrow space, with a potentially dry acoustic, it mattered where you sat. I was lucky to be smuggled to the front by a trio of dedicated festival-goers (one had come for the full three weeks annually for the past 35 years. He deserves a discount). Next to me a local 12-year-old, a budding pianist of evident achievement, sat glued. His enthusiasm was infectious. Concerts are collective events, especially during festivals. These factors, and the proximity of Buchbinder himself, dapper in a suit, not one strand of hair out of place – I had only heard him on disc before – added much to the sum of the parts. There are nine concerts in all.

There was more Beethoven, Op 18 No 4, from the youthful but well-established Modigliani Quartet, in the Queen’s Hall chamber series (relayed live on Radio 3). This French ensemble is beautifully modulated, in the sense that every player has equal presence and voice, expressed with dashing fervour in Dohnányi (Quartet No 3) – the interruption of a broken string notwithstanding – and gossamer brilliance in Ravel’s only quartet. This is worlds away from the mood of bawdy sauciness and wit that characterises the same composer’s operatic double bill, L’heure espagnol and L’enfant et les sortilèges, which returned to Glyndebourne in Laurent Pelly’s richly inventive 2012 staging.

Danielle de Niese was comically voluptuous as Concepción, cheating on her watchmaker in triple time, and in a dramatic change, touchingly boyish and clumsy as the Child in L’enfant. She recently gave birth and sprained her ankle, not at the same time as far as I know. There was no evidence of either: a brave achievement and a dazzling performance. Designs and costumes are exquisite, cast strong, orchestra under the baton of music director Robin Ticciati sensuous and precise; all told, a sumptuous revival as Glyndebourne 2015, with a fortnight to go, nears its successful end.